neovim/runtime/lua/vim/_defaults.lua

--- Default mappings
do
  --- Default maps for * and # in visual mode.
  ---
  --- See |v_star-default| and |v_#-default|
  do
    local function region_chunks(region)
      local chunks = {}
      local maxcol = vim.v.maxcol
      for line, cols in vim.spairs(region) do
        local endcol = cols[2] == maxcol and -1 or cols[2]
        local chunk = vim.api.nvim_buf_get_text(0, line, cols[1], line, endcol, {})[1]
        table.insert(chunks, chunk)
      end
      return chunks
    end

    local function _visual_search(cmd)
      assert(cmd == '/' or cmd == '?')
      local region = vim.region(
        0,
        '.',
        'v',
        vim.api.nvim_get_mode().mode:sub(1, 1),
        vim.o.selection == 'inclusive'
      )
      local chunks = region_chunks(region)
      local esc_chunks = vim
        .iter(chunks)
        :map(function(v)
          return vim.fn.escape(v, cmd == '/' and [[/\]] or [[?\]])
        end)
        :totable()
      local esc_pat = table.concat(esc_chunks, [[\n]])
      local search_cmd = ([[%s\V%s%s]]):format(cmd, esc_pat, '\n')
      return '\27' .. search_cmd
    end

    vim.keymap.set('x', '*', function()
      return _visual_search('/')
    end, { desc = ':help v_star-default', expr = true, silent = true })
    vim.keymap.set('x', '#', function()
      return _visual_search('?')
    end, { desc = ':help v_#-default', expr = true, silent = true })
  end

  --- Map Y to y$. This mimics the behavior of D and C. See |Y-default|
  vim.keymap.set('n', 'Y', 'y$', { desc = ':help Y-default' })

  --- Use normal! <C-L> to prevent inserting raw <C-L> when using i_<C-O>. #17473
  ---
  --- See |CTRL-L-default|
  vim.keymap.set('n', '<C-L>', '<Cmd>nohlsearch<Bar>diffupdate<Bar>normal! <C-L><CR>', {
    desc = ':help CTRL-L-default',
  })

  --- Set undo points when deleting text in insert mode.
  ---
  --- See |i_CTRL-U-default| and |i_CTRL-W-default|
  vim.keymap.set('i', '<C-U>', '<C-G>u<C-U>', { desc = ':help i_CTRL-U-default' })
  vim.keymap.set('i', '<C-W>', '<C-G>u<C-W>', { desc = ':help i_CTRL-W-default' })

  --- Use the same flags as the previous substitution with &.
  ---
  --- Use : instead of <Cmd> so that ranges are supported. #19365
  ---
  --- See |&-default|
  vim.keymap.set('n', '&', ':&&<CR>', { desc = ':help &-default' })

  --- Map |gx| to call |vim.ui.open| on the identifier under the cursor
  do
    -- TODO: use vim.region() when it lands... #13896 #16843
    local function get_visual_selection()
      local save_a = vim.fn.getreginfo('a')
      vim.cmd([[norm! "ay]])
      local selection = vim.fn.getreg('a', 1)
      vim.fn.setreg('a', save_a)
      return selection
    end

    local function do_open(uri)
      local _, err = vim.ui.open(uri)
      if err then
        vim.notify(err, vim.log.levels.ERROR)
      end
    end

    local gx_desc =
      'Opens filepath or URI under cursor with the system handler (file explorer, web browser, …)'
    vim.keymap.set({ 'n' }, 'gx', function()
      do_open(vim.fn.expand('<cfile>'))
    end, { desc = gx_desc })
    vim.keymap.set({ 'x' }, 'gx', function()
      do_open(get_visual_selection())
    end, { desc = gx_desc })
  end
end

--- Default menus
do
  --- Right click popup menu
  -- TODO VimScript, no l10n
  vim.cmd([[
    aunmenu *
    vnoremenu PopUp.Cut                     "+x
    vnoremenu PopUp.Copy                    "+y
    anoremenu PopUp.Paste                   "+gP
    vnoremenu PopUp.Paste                   "+P
    vnoremenu PopUp.Delete                  "_x
    nnoremenu PopUp.Select\ All             ggVG
    vnoremenu PopUp.Select\ All             gg0oG$
    inoremenu PopUp.Select\ All             <C-Home><C-O>VG
    anoremenu PopUp.-1-                     <Nop>
    anoremenu PopUp.How-to\ disable\ mouse  <Cmd>help disable-mouse<CR>
  ]])
end

--- Default autocommands. See |default-autocmds|
do
  local nvim_terminal_augroup = vim.api.nvim_create_augroup('nvim_terminal', {})
  vim.api.nvim_create_autocmd('BufReadCmd', {
    pattern = 'term://*',
    group = nvim_terminal_augroup,
    desc = 'Treat term:// buffers as terminal buffers',
    nested = true,
    command = "if !exists('b:term_title')|call termopen(matchstr(expand(\"<amatch>\"), '\\c\\mterm://\\%(.\\{-}//\\%(\\d\\+:\\)\\?\\)\\?\\zs.*'), {'cwd': expand(get(matchlist(expand(\"<amatch>\"), '\\c\\mterm://\\(.\\{-}\\)//'), 1, ''))})",
  })

  vim.api.nvim_create_autocmd({ 'TermClose' }, {
    group = nvim_terminal_augroup,
    desc = 'Automatically close terminal buffers when started with no arguments and exiting without an error',
    callback = function(args)
      if vim.v.event.status == 0 then
        local info = vim.api.nvim_get_chan_info(vim.bo[args.buf].channel)
        local argv = info.argv or {}
        if #argv == 1 and argv[1] == vim.o.shell then
          vim.cmd({ cmd = 'bdelete', args = { args.buf }, bang = true })
        end
      end
    end,
  })

  vim.api.nvim_create_autocmd('CmdwinEnter', {
    pattern = '[:>]',
    desc = 'Limit syntax sync to maxlines=1 in the command window',
    group = vim.api.nvim_create_augroup('nvim_cmdwin', {}),
    command = 'syntax sync minlines=1 maxlines=1',
  })

  vim.api.nvim_create_autocmd('SwapExists', {
    pattern = '*',
    desc = 'Skip the swapfile prompt when the swapfile is owned by a running Nvim process',
    group = vim.api.nvim_create_augroup('nvim_swapfile', {}),
    callback = function()
      local info = vim.fn.swapinfo(vim.v.swapname)
      local user = vim.uv.os_get_passwd().username
      local iswin = 1 == vim.fn.has('win32')
      if info.error or info.pid <= 0 or (not iswin and info.user ~= user) then
        vim.v.swapchoice = '' -- Show the prompt.
        return
      end
      vim.v.swapchoice = 'e' -- Choose "(E)dit".
      vim.notify(('W325: Ignoring swapfile from Nvim process %d'):format(info.pid))
    end,
  })
end